This is biggest Barbra Streisand.
Trump broke all previous records of votes received in republican caucus. If you subtract the stolen votes by Rafael Cruz, Trump is the actual leader.
Therefore the obvious conclusion is that Trump was successful in bringing voters to the caucus.
There was an interesting piece in Politico (yeah, I know) called ‘portrait of a Trump town’ or some such. It was a photo essay of Ottumwa, Iowa. pretty interesting.